Electric furnace and transformer for use therewith.



F. E. BERRY.

ELECTRIC FURNACE AND TRANSFORMER FOR USE THEREWITH.

- APPLICATION FILED JAN/19.1918.

1,299; 6 64. Patented Apr. 8,1919.

L U ED ST E PA E OFF-10E.

le a- To all hom it may concern Be it'k-nown that I, FREDERICK EDMUNDBERRY, a subject of the King of Great Britain and Ireland, residing at.Hayes, in the county of Middlesex, England, have invented Improvementsin or Relating to Electric Furnaces and, Transformers for Use Therewith,of, which the following is a specification.

- This invention-has reference to improved arrangements of three phasetransformers known ways so so istracted as phase transformers may becoupled up for and electric-furnaces, designed to give a betterdistribu-tionof heat tlrrough the bulk of the metal or charge in thefurnace and abet-' ter mixing of the molten metal or charge,

For. this purpose" in a transformer a rthe {invention there is used athree phase 'transformerthe primary windings, of which can delta or starconnected, or inter-con-- nected star, or'be a combination of suchgroupings, but thesecondary windings of which aresoarranged that eachphase is brought out to separate terminals so as to give at thetransformer itself a separate circuit for each phase. "The secondarywindings ,may be connected up in any 1 of the long as a separate circuitis provided for eachphase.

The three phase transformer may be cona single structure, or threesingle three phase working as well understood.

The three pairs of terminals of the secondary windings are combined withan electric furnace in such manner that three of them form an upper setof terminals or electrodes and the'fothr three are disposed at the lowerpart of fit-he furnace, to form a lower set of terminals or electrodesthat are spaced apart and are in contact, it may be, with the lining ofthe furnace and in electrical connection with the metallic chargein suchfurnace.

In order that the invention may be readily understood it will now befurther described with the aid of' the drawings filed withourprovisional specification.

,In these drawings, Flgure 1 shows, d1a grammatically, a three phasetransformer and electric furnace according to the invention and Fig. 2is a plan showing the relative positions of the secondary termlnals orelectrodes in the furnace.

For simplicity, Fig. 1 shows a three phase transformer having itsprimary windings 1 FREDERICK EDMUND BERRY, or HAYES, ENGLAND. j l I v iI Q 7 K 1 l V ELECTRIC FURNACE AND TRANSFORMER FOR USE 'THEREWITH.

Specification of Letters Patent. Patented Apr, 8 1919, Applica'tionfiledJanuary 19, 1918. Serial No. 212,747. I

a, b and 0 delta connected and its secondary w nd ngs arranged to formthree separate windings d, e and f. I

The corresponding ends of the secondary or phase windings d, e and f areconnected to electrodes 1, 2 and 3 at the top of the furnace and theopposite ends of such windings are connected to terminals 1, 2*, and 3arranged in the lower part of the side portions of the furnace so as tomake contact with the metal charge therein at the periphery thereof, or,.as is more usual, with the lining of the furnace which, at a hightemperature, is conducting so that-the circuit through the-metal iscompleted through such lining.

The relative positions of the electrodes 1, 2 and 3 and terminals 1 2and 5 in the furnace may be varied.- Thus, the positions of theelectrodes 1, 2 and 3 in the upper part of the furnace may be thereverse of those of the terminals 1*, 2 and 3 in the body of thefurnace, as shown in Fig. 1,'so that the 'movement of the metal in theupper part of furnace, due to the current and to'the "electromagneticeffect of such current, will be in't'he opposite direction to themovement of the metal in the lower part of the furnace, so as to moreeffioient-ly mix the metal" and bring all parts thereof under theinfluence of the heat produced by the passage of the current through thefurnace.

- The described arrangement of the transformer and the electrodes andterminalslconnected thereto, constitutes in effect, a six phasecqnnection'tothe furnace. Each of the circuits 1 to l 2 to 2*, 3 to 3,are single phase circuits but the effect of the currents at theelectrodes 1, 2 and 3 and also at the terminals 1 2 and 3 is to give athree phase distribution with corresponding movement. and mixing of themetal in the furnace, and, as hereinbefore stated, the disposiition oftheelectrodes 1, 2 and 3 and the terminals 1*, 2 and 3 may be such as tocreate opposite movements in the metal influencedat these positions soas to improve the mixing of the rectal.

The secondary winding (Z, 6, or f of each phase should be so designed asto give the correct voltage necessary to supply the current requiredagainst the resistance of the are between the corresponding electrode 1,

lining, in addition to the resistance of the winding itself and theconnections external to the transformerand furnace.

If necessary, when starting up the fur vnace, or at'any subsequentperiod if desired, the terminals 1, 2* and 3 in the furnace lining maybe short cirouited by a suitable switch, either actually at theterminals themselves or at the terminal-s of the transformer windingsthat are connected to these-'ipoin'ts.

In this case the arrangement becomes-that of a simple three phasesupply,

Thetransform'er may of course be fitted with primary or secondarytap'pings for varying the voltage to the furnaceas re quire-d. 1 Y

By the arrangement described a better distribution of the heat in .thefurnace is effected and a better mixing of the metal or charge -in thefurnace obtained, whereby a v more etlicient working ofthe furnace isinsured and smaller electrodes can be used for the same heating effectthan with other arrangements" of combined transformer-and electricfurnace heretofore used,

.lVhat I claim is 1. A three phase electric furnace having upperelectrodes arranged above the furnace charge and lower and laterallyarranged electrodes in electrical connection with. said charge when thefurnace 1s'1n operation each of said lower electrodes "being ofsuchdimensions and so arranged that it is located wholly at a part of thefurnace wall that will be between the top and bottom of the furnacecharge when the furnace -1s in acti )ll.

2. A three pha*e electric furnace according to claim 1', 4 herein eachof the lower electrodes'is embedded. in the side wall-of the furnace andabove the bottom of the furnace so that it willbe separated fromthefurnace charge by furnace.

i 3. A three phase electric furnace according to the claim 1, whereirthe polarities of the electrodes in the upper part of the furnace arethe reverse of those in the. lower part thereof.

4. A three phase electric furnace having upper electrodes arranged abovethe furnace charge and lower and laterally arranged electrodes inelectrical connection with the said charge when the furnace is inoperation, each of said lower electrodes being of such dimensions and soarranged that it is located whollv at a part of the furnace wall part ofthe refcartory wall of the that will be between the top and bottom ofthe furnace charge when the furnace is in operation, and means wherebythe lower electrodes can, when desired, be temporarily shortcircuited'outside the furnace.

'5. A threep hase electric furnace according to claim 1 combined withthree secondary winding of atransformer, said windings being separatefrom each other and each 4 having its two ends connected respectivelytoanv upper electrode and a lower electrode..

6. An electric furnace and a three phase electrical transformer having adelta con nected primary winding and three separate secondary windings,said furnace having three pairs of upper and lower electrodes, eachpairbeing connected to the ends of one of saidseparate secondary windingsand each of the lower electrodesbeing of such dimensions and so arrangedthat it is located at a. part of the furnace wall that will be betweenthe top and bottom of the furnace charge when the furnace is in action.

7. An electric furnace and a three phase A electrical transformer havinga delta connected primary-winding and three separate secondary windlngs,said furnace having three pairs of upper and lower electrodes,

each pair being connected to the ends of one of said separate secondarywindings and each of the lower electrodes being of such dimensions andso arranged that it is located at a part of the furnace wall that willbe between the top and bottom of the furnace charge when the furnace isinaction at a part of the furnace wall that will be be'-.

tween the top and bottom of the furnace charge when the furnace .is inaction and a short circuiting device adapted to short cir.

cuit the electrical connections between the lower electrodes and thecorresponding ends of the separate secondary conductors.

Signed at London, England, this 21st day of December, 1917.

FREDERICK EDMUND BERRY.

